Operator: comprehend-pageside

Problem space: top-ps
Operator Overview:
This operator adds the side (left hand or right hand) of the page currently being viewed to the situation model, so that we can make appropriate choices about how to go to the next page, where to find the page number, etc.

Operator Proposal:
The operator is proposed when we are scanning the page for the pagenum, as a result of the find-pagenum operator's selection in the search-for-step problem space. The operator takes the page side as an argument.

Operator Application:
The operator is applied by adding the value to the situation model.

Operator Reconsider:
The operator is reconsidered as part of the application.
The operator is proposed in scan-page.soar6, but implemented in comprehend.soar6.